The present invention relates to the field of aviation and more particularly to an aircraft cargo handling system.
Commercial aircraft cargo handling systems have traditionally been designed to take advantage of standardized cargo containers and pallets. These standardized containers and pallets are often referred to as unit load devices or ULD's. ULD containers are closed containers typically made of aluminum with a base having rectangular dimensions with a lip sized to fit between a pair of standard width guide rails within the aircraft cargo hold. One example of a ULD container is an AMJ container, which is a contoured main deck container having base dimensions of 96 inches wide by 125 inches long, with a height of 96 inches.
ULD pallets are typically formed from an aluminum skin covering a lightweight core. ULD pallets have rectangular dimensions standardized to fit between the same guide rails in the aircraft hold as a corresponding ULD container. One example of a ULD pallet is known as a Code M pallet, which is a rectangular sheet 96 inches wide by 125 inches long.
The United States Department of Defense has also adopted a cargo handling system that utilizes standardized pallets. The Air Force cargo handling system is known as “Materials Handling Support System 463L” or simply “463L System.” The standard pallet used in the 463L system is known as the HCU-6/E pallet and measure 88 inches wide by 108 inches long and is 2¾ inches thick. The edges of the pallet have a castellated or “sawtooth” edge where there is a 3 inch gap in the guide surface approximately every 15 inches. This is in contrast to commercial pallets, which have smooth edges on all sides.
Aircraft that participate in the Civil Reserve Air Fleet (CRAF) must be readily convertible from carrying standard ULD pallets such as the Code M pallet to carrying the Air Force's 463L pallets. Unfortunately, the castellated edge of the 463L pallet is often incompatible with the center guides on wide-body aircraft. This is because the center guides utilize relatively short, T-shaped guide posts which can fall into and catch on the 3 inch gaps in the 463L pallet edge. Additionally, the shorter width of the 463L pallet means that there is substantial wasted space along the sides and/or down the center between the rows of pallets in the cargo hold. Accordingly, a significant benefit could be gained if Air Force 463L pallets could be loaded asymmetrically so that one row of pallets is loaded with the long dimension parallel to the airframe and a second row loaded adjacent the first row with the long axis of the pallets perpendicular to the axis of the aircraft. Although it would be possible to remove and replace the center guide system each time the aircraft were converted from civilian to CRAF use, the reconfiguration would render this approach impractical. Many operators would prefer to leave the center guide system installed to avoid the time and labor necessary to remove and replace the hardware.